I like to caution the idea of assuming respected manufacturer’s lights are accurate and consistent throughout. I just posted some ceiling bounce results for my AA lights and there are several identical lights from “respectable” companies that show considerable variation in light output. My ceiling bounce measurements have been extremely consistent even when measuring the same light months apart.
Also I prefer we don’t apply our own correction factor and instead apply a standard correction factor among all the lumen tubes. One of the main benefits of so many people owning TA lumen tubes is so we have a standardized basis to compare lumens among members. Even if the lumen tubes are not calibrated to realistic lumens, they are still calibrated consistently among all the units so we need to come up with standardized correction factor.
M43 is very consistent. Output remains constant all the way down to 3.5V (boost driver). I’ve got three identical, and output is very close to each other.
Yes, as they were setup at the start looks to be pretty close to what they need to be. Although they have now been calibrated up to match the rest so it really doesn’t apply now.
TA, is your plan to get a couple of properly measured lights from Maukka and then figure out a simple and repeatable way to reduce output on the sensor?
I would much rather we do that so that we can still use the numbers directly off the Lux meter. I realize we can just use a correction factor and do the math, but that’s not ideal to me. We can still make these tubes live up to the intended expectations.
BTW, I’m going to put off measurin all my lights for a few days when I have more time. Plus other people will be receiving theirs. We will get it sorted out. :+1:
Yes, my goal is to get a good calibration figured out first and this try to figure out a way to calibrate the spheres.
Mailing them back to me is the best way then I can calibrate them directly.
Or if you have a nice stable light you can take some before measurements and calibrate it yourself.
Or if I can find a way to add something that will adjust them that I can mail out that would be cool but after having messed with these, I doubt that is possible.
We just need to find a consistent, thin, film-like material that we can layer up.
A paper-based product would certainly be cheap, but I’m not sure of its consistency. I think you share the same concerns. Maybe we can test a variety of thin papers.
What about a lens that can be bought and stuck into the hole that the sensor mounts into? Kind of like a neutral density filter but fairly weak. I’ve got that ND filter you sent me and that thing really knocks down the lumens. I have to multiply my readings by 13.1. This should be more consistent, but the odds of getting exactly the right reduction in output seems a bit slim.
I will do some more experiments next week and report back.
Based on the results from fifteen lights (manufacturer spec vs TA Tube), my average correction factor would be .728
Later, if we need a standard across all units, I can also use that. But for now, that number makes the tube useful for me until everything gets sorted out.
If others can post their correction factor, it would be interesting to see if the results are close - or not.
When you say spec, do you mean the lumens the light is advertised to be?
Compared to the JoshK sphere, my numbers (roughly) are around .65 to .70, so pretty close to your .73. We are in the same ballpark. :+1: Of course, this all needs to be decided later on.
We should also try to standardize the time we measure. ANSI-FL1 says 30 seconds. That might be our standard time unless we state otherwise.
The batteries also can make a difference with certain lights. I have 26650 blue and black Liitokala’s that are low IR. I’ve also got some low IR button top 30Q. I can have several on the charger as I’m using one. Then put it on the charger and grab another so the voltage is always topped off.
I guess I will record the lumens as they come off the stock TA Tube. Then we can probably decide on a specific correction factor at a later time.
I can see this being a fun marathon session when I get a day off.
It is much higher than mine. Base on maukka’s review DATA, my average calibration# for TA’s tube is 0.6730133. The number is not 100% accurate because I know maukka did upgrade & recalibrate his integrating spheres several times.
I use most mid & low mode for more constant output from maukka’s review found on CPF and BLF. I choose seven stock lights same model & CCT as in maukka’s review to calibrate TA’s tube:
Lumintop Tool AAA Copper Nichia
Lumintop Tool AAA Ti Nichia
Zebralight SC600w HI Mk3
Olight H1 Nova NW
Olight S Mini Ti NW
Nitecore EC4SW
Nitecore MH20 NW
I wouldn’t use the Lumintop Tool AAA for any calibration as its driver has been known to vary wildly from one batch to another. I can remeasure the Nitecores when I have time to give you more accurate numbers. It was a long time ago when I tested them.